As Houston continues dealing with the impacts of Hurricane Harvey, officials are focused on how to bolster the city against the next big storm.

But alongside the forward-looking talk about a new reservoir or more cautious development, there’s an effort underway to look back at the storm more closely. Scientists are just starting to explore how Harvey changed the physical world around us.

Off a busy road near the Texas Medical Center, Lisa Montemayor with the city’s health department is collecting water samples. She reaches over a bridge and lowers what looks like a big thermometer into Brays Bayou.

“It’s going to give us the temperature, the pH, the dissolved oxygen,” she explains.

It will be a couple days to a week before the lab results on the water samples she gathered come back, giving her a picture of the bayou’s water quality. Still, Montemayor says researchers do have a basic understanding of the storm’s overall impact.

“The most consistent issue we saw across the city were high bacteria levels, specifically high E. coli levels,” she says. “And we saw those for several weeks in some of our bayous, and in other bayous we saw a return back to normal levels after a few days.”

There is still plenty that researchers don’t yet know.

For example, the city still needs to review test results from pollution sampling near industrial areas and a couple contaminated “Superfund” sites.

“We just want to make sure that we didn’t have any breaches of linings or reason to be concerned about contaminants leaking from those sites,” Montemayor says.

The degree to which Harvey spread pollution is among the many issues scientists are looking into. The National Science Foundation recently awarded millions of dollars in grants for researchers to study everything from the impact on sediment and fish in Galveston Bay, to the toxicity of stormwater runoff.

The University of Houston’s Hanadi Rifai is among those who sprang into action while the city was still flooded.

“We started literally a couple days after [the] hurricane ended,” she says.

The new funding is allowing her team to look for signs of highly-toxic pollution that might have flowed into the city’s bayous.

“We’re looking at things like the presence of metals, we’re looking at things like the presence of industrial pollutants, like polychlorinated biphenyls and dioxins,” she says. “That’s really the longer-term, it stays in the sediment for a long, long time.”

The way Rifai describes it, this kind of research can help reveal some of Harvey’s impacts that might otherwise be hard to notice.

“The spills and leaks and releases that occur during these events, they always leave a footprint behind that is longer-lasting than the storm or other effects from the storm,” she says.

According to the center, Harvey created a “legacy of health concerns”that will “linger for years to come.” Toxins, viruses and bacteria were all found in the floodwaters, along with millions of gallons of untreated sewage.

The storm’s flooding was unprecedented, which raises the question of whether the environmental fallout will be as well. The Gulf Coast has always adapted to extremes, Gonzalez said, but the region’s ever-growing population and development makes for a blurry future.

“These ecosystems that have been altered, re-engineered, stressed – do they still have the ability to adapt, and be resilient, to these types of disturbances?” Gonzalez wonders.

As scientists continue their work, she noted that they are also keeping in mind how the environment might react to a “new normal” of more extreme weather.